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API 5D Ball Valve Seat & Seal Material Selection Guide

API 5D Ball Valve Seat & Seal Material Selection Guide

Ball Valve Seat & Seal Material Selection Guide


Ball valves play a critical role in controlling the flow of fluid and pressure within a pipeline, but their effectiveness and safety is only as good as the seat material used. In this blog post, we are going to review the basics of five commonly used ball valve seat materials.


When choosing a polymer material for a ball valve seat, there are numerous factors that are involved. Key material properties include …

  • Sufficient ductility to provide a reliable seal
  • Dimensional stability to ensure the ball valve seat retains its shape for reliable sealing and performance
  • Very low friction to keep stem torque at a minimum
  • Low coefficient of thermal expansion so that the ball valve seat retains its shape when temperature changes occur
  • Excellent wear resistance for a long service life
  • Chemical compatibility with all media involved

In some operating environments, it is also important that ball valve seat materials exhibit these properties:

  • Low moisture absorption to prevent dimensional changes in the presence of water or high humidity
  • Maintain performance with repeated sterilization that can include hot water, steam, and harsh cleaning chemicals
  • Good performance in the presence of sudden decompression (i.e., pressure drops over 650 psi)
Ball valve seat and seal material specifications: hardness, temperature range, pressure rating, compressive strength for the soft seat ring: PTFE, RPTFE, PEEK, Nylon, Devlon, Molon, etc. Seal material: viton AED etc.
Seat Material Specifictions


Tensile Strength (MPa) 24.8 25.4 75〜100 91
Compressive Strength (MPa) 35 52 100-140 137
Elongation (%) 250 120 10〜30 50
Hardness(SH.A) 56 60 78 82
Water Absorption (%) <0.01 <0.01 0.7 0.12
Specific Gravity (G/cm3) 2.2 2.2 1.2 1.35
Temperature Range (°F) -300~400 -150~425 -40〜300 -150~500
Pressure Rating (Class) 150~600 150~600 150~1500 150~2500
Service Application Chemical & Cryogenic Chemical & Cryogenic High Pressure & Lov/Temperature High Pressure & High Temperature

Seat Material Specifictions (continued)

Nylon, Devlon, Delrin

Nylon 1010 Nylon 12 Devlon V Delrin
Tensile Strength (MPa) 55 60 80 68
Compressive Strength (MPa) 70 79 140 110
Elongation (%) 150 200 5.37 220
Hardness(SH.A) 70 75 78 78
Water Absorption (%) 0.3 0.2 0.1 0.2
Specific Gravity (G/cm3) 1.04 1.01 1.14 1.41
Temperature Range (*F) -40〜200 -58〜250 -150〜300 -58〜230
Pressure Rating (Class) 600〜1500 600〜1500 150〜1500 150-1500
Service Application High Pressures &  Low Temperature High Pressure & Low Temperature High Pressure & Low/Temperature High Pressure & Low Temperature

Note: The soft seat is also called seat ring in floating ball valves; it is called seat insert in trunnion-mounted ball valves.

Seal Material Specifications

Viton A NBR Viton B HNBR(HSN) Viton AED
Temperature range (°F) -20〜400 -50〜250 -20〜400 -40〜320 -20〜480
Hardness (SH.A) 70 70 70 80 90
Specific Gravity (G/cm3) 1.85 1.2 1.85 1.33 1.9
Service Application Petroleum Oils, Gasoline, Transmission Fluid Petroleum Oils, Water, Hydraulic Oils Mineral Acid, Steam, MTBE Petroleum Oils, H2S&CO2 Anti-Explosive Decompression Petroleum Oils, H2S&CO2 Anti-Explosive Decompression

Gasket Material Specifications 

Flexible Graphite Spiral Wound 316+Graphite PTFE SpiralWound Monel + PTFE
Temperature Range °F -300〜900 -300〜900 -300〜400 -300〜400
PH 0〜14 0〜14 0〜14 0〜14
Service Application Fire-safe Fire-safe Cryogenic, High Corrosive High Corrosive


Ball valve seals are used in many different industries, including chemical processing plants, oil and gas operations, manufacturing facilities, food preparation, and even residential use. As a leak-proof means of pressure and flow control, their smooth and reliable operation is critical–which is why polymer materials work extremely well for ball valve seats. If you are in the market for a ball valve seat material, contact the experts at Advanced EMC. We can put our years of experience to work for you, helping you select the right material for your project.

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